I have a forest river flagstaff hw27s/c. It has st205/75r14 tires. Iam looking to get another tire with rim so I have two spares for a family trip to fort wilderness. When I look on the decal it says st205/75r14/c but says the rim size is 13x5.5? How the heck iam I getting a 14 inch tire on a 13 inch rim?